This specification refers to integrated semiconductor devices, in one embodiment to smart power integrated semiconductor devices, having a protecting structure between different parts thereof and a manufacturing method therefor.
Many functions of modern devices in automotive, consumer and industrial applications such as driving a motor or an electric machine are controlled by Electronic Control Units (ECUs). In automobiles, for example, igniting an airbag, switching the valves of an ABS on and off, and injecting fuel into the cylinders of the motor are activated and regulated, respectively, by different decentralized ECUs. Even many home appliances like a washing machine and a dish washer are controlled by ECUs. Typically, an ECU includes analog, digital and power modules and at least one microcontroller (μC). To minimize cost, size and weight of the electronics, the digital and analog circuits of an ECU are typically monolithically integrated on a common substrate as a single integrated circuit (IC). Depending on the application, this can e.g., be achieved in a HV-CMOS technology or in a smart power technology. While HV-CMOS technology combines high-voltage MOS (HV-MOS) and CMOS transistors, smart power technology offers in addition bipolar transistors for high precision analog functions, and DMOS transistors to drive loads up to several amperes.
Electrostatic discharge (ESD) pulses occurring during assembly and energetic electric pulses during operation, e.g., due to switching of actuators, should not lead to malfunction or destruction of an ECU. Even simple actuators such as a contact bouncing relay generate repeating over-voltage pulses with fast rise and fall times. With inductive loads, negative voltages may occur during reverse currents as well. Energetic electric pulses typically last a few nanoseconds up to several milliseconds. Many of these pulses have been standardized in the ISO-7637. Some of these pulses which are in the range of nanoseconds are similar to ESD pulses. Even if the pulses do not destroy the other modules, such pulses may induce noise into the substrate (“substrate potential fluctuations”) and hence function as a noise source for the other modules. This may result in a shift of the operating point or a complete intermittent fault of these modules during operation. For example, negative voltage pulses injected into a motor driver module, in particular for drive loads in the ampere range, may provide a significant noise source for an analog measuring module and/or a logic module. To ensure high reliability it is, therefore, often desirable to efficiently insulate or decouple the different modules of the IC from each other. In doing so, any cross-talk between the modules is eliminated or at least reduced. Consequently, a pulse injected into one module of the IC is mainly dissipated or absorbed within the respective module. Thereby, the other modules can be protected. This is particularly important in automotive electronics for which the reliability requirements are one or two orders of magnitude higher above those of standard technologies. Insulating the modules of an IC from each other reduces, in addition, the cross-talk between the different modules over the common substrate which results from the operation of the modules themselves. Typically, this cross-talk becomes more important with increasing level of integration. Furthermore, insulating the modules on chip level reduces costs as the protection elements are integrated into the ICs.